Automatic control



J. J. NEUMAN Jan. 24, 1939.

AUTOMAT .TC CONTROL Original Filed Jan. 15, 1936 ,l i i,

Snventor bmoats-weumm (Ittor eg Patented Jan. 24, 1939 UNITED, STATES PATENT OFFICE AUTOMATIC CONTROL Company, New York South Salem.

N. Y., a company of Original application January 13, 1938, Serial No.

1 Claim.

The present invention relates to an automatic sweetwater control to screw conveyer under extractor machine; and is a division of United States patent application Serial No. 58,804, filed by me under date of January 13, 1936, now Patent No. 2,098,591.

In the process of refining sugar the raw sugar is processed through primary centrifugal extractor machines. This sugar is discharged from these machines in a semi-dry state into screw conveyers. These conveyers then convey the sugar to a melter tank where the sugar is melted by mixing with water and heating.

In the process it is necessary that a fixed density be maintained. If it were possible to run this hot water into the screw conveyer instead 01' adding it at the melter; some very definite advantages would be obtained.

First, the sugar would be mixed thoroughly in m the screw with the water and thereby relieve the duty on the melter.

Second, the sugar being mixed'with hot water in the screw, will run freely and require less than one-tenth of the power to operate the screws.

In the past, attempt has been made to accomplish this objective by manual control but with very unsatisfactory results due to the fact that at times insufiicient water was applied and then the power would be greater than without the application of water as the sugar would get into a form similar to bakers dough or paste; at other times too much water was applied which was very unsatisfactory for the processes which succeeded the melting.

35 An object of the present invention is, there- A still further object is to provide an electric controlling apparatus by means of which the other objects are carried out.

Yet another object is to use in this electric apparatus a magnetic relay possessing the following features: adjustable to operate at various current values; an adjustable core to alter the magnetic flux; 2. by-pass device for temporarily short 55 circuiting the magnetic flux; an arrangement Divided and this application April 1936, Serial No. 74,248

whereby two circuits may be controlled simultaneously by the relay; a further arrangement for controlling two circuits wherein one is opened or closed before the other.

In the drawing wherein the same reference characters refer to like or corresponding parts:

Figure 1 is a side elevation of a unit employing the present invention, with the circuits shown in diagram and parts in section.

Figure 2 is an enlarged detail side elevation of the relay control for the sweetwater, with part of the coil broken away.

Figure 3 is a top plan view of a relay; modified to control two circuits and Figure 4 is a sectional fragment of the device of Fig. 3 taken in the region corresponding to the line 4-4 of Figure 2.

In Figure l, the centrifugal extractor Ill, having a revolving basket ll driven through a shaft I2, is suspended over the screw conveyer i3 which carries sugar to the melter tank Ma. The screw conveyer I3 is composed of a tube l4 within which is mounted the screw l5 driven by the motor i6 through the reducing gears II.

In the upper end of the conveyer tube I4 is located a spray head i8 for the purpose of adding melting water to the sugar in the conveyer l3.'

The spray i8 is connected with a water source by the relay in the circuit of the motor i6. Electric current for the motor i6 is drawn from the supply line 2| through the leads 2| a and 2") and controlled by the motor switch 22.

In operation the extractor l0 builds up a wall of sugar 23 on the sides of its basket H. This accumulation is removed and permitted to fall into the conveyer l3 where it is mixed with water entering through the spray i8 and carried to the melting tank l4a. At the melting tank 14a the sugar and water are heated by steam or other coils 24 and agitated by a motor driven paddle 25 to complete the dissolving, after which the solution is removed and the sugar continued through the remaining steps of. the process.

This invention concerns particularly the automatic control of the melting water sprayedinto' the conveyer l3. As the sugar accumulates in the extractor I0 the switch 22 is closed starting the motor i6 and driving the screw IS. The relay 20 is normally closed energizing the solenoid 26 of the water valve l9 and closing the same. This relay 20 has a predetermined operating range so that at low current values in the motor circuit the switch 20a remains closedbut at a definite higher value the switch 20a opens. As the dry sugar enters the conveyer I3, the screw l5 meets increased resistance and the motor It draws more current. The added current flowing through the relay 2|! causes the opening of the circuit through the solenoid 26 allowing the valve |9 to open' under the force of its spring 21 thus admitting water to the conveyer 3. As water is mixed with the sugar the resistance of the screw l5 drops with a consequent drop in current passing through the motor |6. As the current drops below the minimum required to open the relay 20, it closes again completing the circuit through the solenoid 26 and closing the valve I 9.

The relay 20, which is in the motor circuit, is of the electromagnetic type, the primary circuit being through the coil 28, and the secondary being controlled by a mercury switch 29, as shown in detail in Figures 2, 3 and 4.

The coil 28 is held in a soft iron cap 30 by a bottom plate 3| of some non-magnetic material such as brass. The top of the cap 30 is drilled and tapped over the hollow core portion of the coil 28 to receive the threaded soft iron core piece 32 which is thereby adjustable in the core to vary the efiect of the magnet. A locking nut 33 is provided to hold the core piece 32 in adjustment.

The mercury switch 29 is suspended at the bottom of the magnet by the usual form of brass bracket 34, carrying clips 35 adjustable with respect to the magnet by movement in the slots 36 of the bracket 34. The mercury switch 29 employed comprises a glass tube 37 having a mercury well 38 at each end, and a wire 39 of a magnetic material bridging the wells 38. The glass tube 31 is partially evacuated and contains a gas of arc quenching and heat conducting properties. The magnetic field is concentrated beneath the coil 28 by the use of a small iron core piece 40 in the lower part of the hollow core and resting on the plate 3|. A bar 4|, likewise of a magnetic material, is held against the underside of the plate 3| by bolting to the small core piece 40 by a steel screw 42, the magnetic field being thus concentrated in the bar 4|.

By adjusting the magnet strength, by moving the core piece 32, and also by moving the mercury tube 29 to or away from the bar 4|, the point at which the valve I9 is opened and water admitted to the conveyer |3 may be varied. For accomplishing a temporary shortening of the magnetic flux a threaded soft iron plunger 43 is passed through the side of the cap 30 and the plate 3| extending inward towards the bar 4|. At the outside of the cap 30, the plunger 43 is provided with a non-magnetic head 44 afiording a means for rotating the plunger 43 to cause it to short circuit more or less of the magnetic flux to the cap 30 thus raising the minimum current .required to lift the wire 39. Its purpose is to short circuit a portion of the magnetic flux. When motors and conveyers start up they are cold and draw more current for several hours until warmed up. By pushing in the plunger 43 a portion of the magnetic flux is by-passed between the cap 30 and the bar 4| and the switches 29 are thus not operated as would normally be the case when a current passed which is in excess of that for which the core piece 32 has been adjusted. After the machine is warmed up and drawing normal current the operator pulls out the plunger 43. Spacing washers 45 are placed between the head 44 and the cap wall 30 to limit the extent of inward movement of the plunger 43. The washers 45 are added in suflicient number to permit the plunger 43 to be pushed in enough to by-pass a portion of the flux just suflicient in quantity to prevent the relay 20 from operating at the normal current during the warm up period. If too much were by-passed the relay 20 might fail to operate even at a serious overload.

Figures 3 and 4 show a modification in which two mercury switches 29 are used. The relay 20 in such a case may be used as a two pole single throw switch and so may control two circuits. The circuits will be controlled simultaneously if similar mercury tubes 31 are used and they are held at the same distance from the bar 4|. It may be of value to have one circuit open before the other, in which case the bar 4| will be provided with a stepped portion 46 as shown in Figure 4 so that one of the supporting brackets 34 will be lower than the other and the mercury tube 31 will be correspondingly removed from the magnetic field with the result that a stronger field will be required to open it.

The relay 20 is adjusted as follows: With the coil 28 in the motor circuit connected to the leads 2|b and 2|c, the core piece 32 is screwed out almost to the top. With the motor l6 running and normal current flowing screw down the core piece 32 until the wire 39 is lifted, then retract the core piece 32 a turn or so to allow a slight excess of current without operating the relay 20. This margin of excess is best determined by trial for the individual case. When the core 32 is properly adjusted-the lock nut 33 is tightened to prevent further motion.

It is obvious that various changes and modifi cations may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claim.

I claim:---

An electromagnetic relay having a motor, comprising a coil in the circuit of said motor, a bar of magnetic material beneath the coil to concentrate the magnetic flux therein, and a pair of magnetic mercury switches suspended from the ends of said bar and controlling circuits, one end of said bar being cut away at the top to provide a seat for one switch lower than that at the opposite end, the switch being thereby further removed from the bar and reacting only to greater flux than the nearer switch.

JACOB J. NEUMAN. 

